Iraq has one of the worl's oldest cultural histories. See: History of Iraq. Unlike many Arab countries, it embraces and celebrates the achievements of its past in pre-Islamic times. What is now Iraq was once part of the Cradle of Civilization in ancient Mesopotamia and the culture of Sumer, from which the first known wheel was recovered, flourished there. In the 8th century and 9th century the Islamic Abbasid Caliphs presided over what was then the world's leading civilization, rich in science, art and literature.